Abstract
In order to effectively meet the working temperature requirements of DPF active regeneration under mediumlow speed and load conditions, engine bench test was used to study the influences of active control measures such as main injection timing, near post injection and late post injection parameters on incylinder combustion process, exhaust thermal status and emission performance under the medium and low load steady state conditions. The steady test results showed that the ignition delay period shortened, the combustion duration prolonged, the incylinder maximum combustion pressure and peak temperature decreased, the instantaneous heat release rate dropped, the center of gravity shifted back, BSFC and smoke increased slightly and the temperature of DOC inlet rose little after main injection timing delayed. The introduction of near post injection reduced the peak combustion pressure, but the second peak value of instantaneous heat release rate and post combustion period increased. In addition, the reasonable matching of near post injection quantity and angle between main and near post injection could improve the inlet temperature of DOC properly, and the highest increase was up to 19.3%. It could also effectively improve smoke and NOx emission. The increase of late post injection quantity could significantly increase the inlet temperature of DPF by up to 70%, but it would lead to an increase in BSFC and HC escape. According to the distribution state of exhaust temperature in the whole working condition of prototype engine, the strategy of temperaturerising injection control in each region was proposed. The low load area adopted fuel injection combination of near and late post injection accompanied with a large amount of fuel injection. At medium and high load area, the near post injection reduced step by step and finally stopped, and the main injection advanced appropriately at the same time.
Key words
diesel engine；exhaust thermal management；diesel particulate filter(DPF)；active regeneration /
combustion process；emission characteristic
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WANG Jian，CAO Zheng，ZHANG Duojun，LIU Shengji.
Fuel Injection Control Strategy Based on Exhaust Thermal Management of Diesel Engine[J]. Vehicle Engine. 2018, 0(2): 79-86 https://doi.org/10.3969/j.issn.1001-2222.2018.02.014
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